JP2009156968A - Image fixing device, image forming apparatus, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image fixing device capable of suppressing deterioration of a heat member due to heat by highly accurately estimating the temperature thereof, and to provide an image forming apparatus and a program. <P>SOLUTION: When a control section detects the turning on of a power source (S101), a heat control section acquires, from a time measuring section, information on time that has passed since the power source is turned off (S102), and determines whether a predetermined time has passed (S103). An operating section acquires information necessary for an estimating operation from a temperature detecting section, a power detecting section, and a storage section (S104). Based on the temperature of the heat roll as an initial temperature, the operating section performs the estimating operation for control exerted to estimate the surface temperature of the heat roll (S105). The heat control section determines whether the surface temperature of the heat roll is nonuniform (S106). If it is determined that the temperature is nonuniform, the heat control section determines a control method (S107), operates a warm-up operation and brings it into a ready state (S108 to 110). Subsequently, it is determined whether to correct layer thickness information for the elastic layer of the heat roll, and a correction is made if necessary (S111 to 113). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image fixing device, an image forming apparatus, and a program.

  In an image forming apparatus such as a printer or a copier using an electrophotographic method, first, an electrostatic latent image formed by a known electrophotographic process is developed on a toner image holding body on the surface of an image holding body made of an organic photoreceptor. To do. Next, the toner image is electrostatically transferred onto a recording medium (such as paper) by a transfer device, and then the toner image is fixed on the recording medium by a fixing device, thereby forming an image.

  The fixing device generally includes a heat fixing roll including a heated roll and a pressure roll that are rotationally driven. Heat and pressure are applied to the recording medium by passing the recording medium onto which the toner has been transferred through the contact width (nip) portion formed between these heat fixing rolls. As a result, the unfixed toner on the recording medium is melted and fixed (fixed), and then discharged out of the image forming apparatus.

  In order to extend the life of a heating roll that continues to receive high-temperature heat from a heating source during use of the image forming apparatus, it is necessary to stabilize the heating roll at a predetermined temperature. Therefore, for example, a technique is used in which the surface temperature of the heating roll is detected by a temperature detection sensor, and the on / off of the heating source and the switching of the heating source are controlled.

  On the other hand, a technique for predicting temperature by calculation by solving an equation based on the law of conservation of heat energy is generally known. A technique for simulation has been proposed (see, for example, Patent Document 1). In Patent Document 1, the amount of heat given to each part of the roller body is calculated by superimposing heat radiated from each position of the light emitting part wound in a coil shape among the filaments of the lamp heater, And the structure which calculates the temperature distribution of each part of a roller main body based on the calculated calorie | heat amount is disclosed.

JP 2006-190499 A

  An object of the present invention is to provide an image fixing apparatus, an image forming apparatus, and a program capable of suppressing deterioration of a heating member due to heat by performing highly accurate temperature prediction.

The invention according to claim 1 is a heat source capable of switching between a plurality of different heat generation distributions, a heating member having a heating area of a predetermined width heated by the heat generation source, and facing the heating member. A pressure member that fixes the toner image transferred to the sheet together with the heating member, and the heating member after heating by the heat source when heating of the heating member by the heat source is started Prediction means for predicting the temperature distribution of the heating region by a predetermined calculation, and one or more used for heating the heating member from the plurality of heat generation distributions of the heat generation source based on a prediction result by the prediction means And a determination unit that determines a temperature difference in the heating region of the heating member to be a predetermined value or less. .
According to a second aspect of the present invention, the determination means is capable of fixing the one or more heat generation distributions and the heating time while a temperature difference in the heating region of the heating member is equal to or less than a predetermined value. The image fixing device according to claim 1, wherein the time until heating is determined to be within a predetermined range.
According to a third aspect of the present invention, the predetermined calculation by the predicting means includes information on the plurality of heat generation distributions of the heat source, information on heat conduction in the width direction of the heating member, and from the heating member to ambient air. 2. The image fixing device according to claim 1, wherein the calculation is performed using information on the heat transfer of the first heat transfer and information on heat transfer from the heating member to the holding member that holds the heating member.
According to a fourth aspect of the present invention, the temperature detection means for detecting the surface temperature of the heating member in a fixable state, and the difference between the prediction result by the prediction means and the detection result by the temperature detection means is calculated. The image fixing apparatus according to claim 1, further comprising a deterioration detection unit that detects deterioration of the heating member.

According to a fifth aspect of the present invention, there is provided an image carrier, a transfer device that transfers the toner image held on the image carrier to a recording medium, and the toner image transferred by the transfer device is fixed on the recording medium. The fixing device includes a heating source capable of switching a plurality of different heat generation distributions, a heating member having a heating area having a predetermined width heated by the heating source, and the heating. A pressure member provided opposite to the member and fixing the toner image transferred to the paper together with the heating member to the paper, and after heating by the heat source when the heating member starts heating by the heat source Predicting the temperature distribution of the heating region of the heating member by a predetermined calculation, and heating the heating member from the plurality of heat generation distributions of the heat source based on a prediction result by the prediction unit. Determining means for determining one or more heat generation distributions and a heating time in the one or more heat generation distributions so that a temperature difference in the heating region of the heating member is a predetermined value or less. Forming device.
According to a sixth aspect of the present invention, the determination unit is capable of fixing the one or more heat generation distributions and the heating time while a temperature difference in the heating region of the heating member becomes a predetermined value or less. The image forming apparatus according to claim 5, wherein the time until heating is determined to be within a predetermined range.

According to the seventh aspect of the present invention, the heating region of the heating member that fixes the toner image transferred to the sheet together with the pressure member to the sheet is heated by a heat source that can switch a plurality of different heat generation distributions. When the heating of the heating member by the heating source is started, the computer device that controls the heating source predicts the temperature distribution of the heating region of the heating member after heating by the heating source by a predetermined calculation. One or more heat distributions used for heating the heating member from the plurality of heat generation distributions of the heat generation source and the one or more heat generation distributions based on the prediction function to be performed and a prediction result by the prediction function And a determination function for determining a heating time so that a temperature difference in the heating region of the heating member becomes a predetermined value or less.
According to an eighth aspect of the present invention, the determination function is capable of fixing the one or more heat generation distributions and the heating time while the temperature difference in the heating region of the heating member is equal to or less than a predetermined value. The program according to claim 7, wherein the program is determined so that a time until the heating is within a predetermined range.
According to a ninth aspect of the present invention, the computer device includes a temperature detection function for detecting a surface temperature of the heating member in a fixable state, a prediction result by the prediction function, and a detection result by the temperature detection function. The program according to claim 7, further comprising a deterioration detection function for calculating a difference and detecting deterioration of the heating member.

According to the first aspect, it is possible to realize optimum temperature control based on a high-speed temperature prediction calculation, and it is possible to suppress deterioration of the heating member due to heat by performing temperature prediction with higher accuracy than conventional.
According to the second aspect, it is possible to realize control that minimizes the temperature difference in the heating member, and to reduce the occurrence of partial overheating when the heating member is heated.
According to the third aspect of the present invention, it is possible to improve the accuracy of the temperature prediction as compared with the prior art by the temperature prediction calculation considering the device-specific information, the device installation environment, and the deterioration state.
According to the fourth aspect, since the deterioration of the heating member is detected at every heating, it is possible to detect the heating member more accurately than in the past, and the result is reflected in the temperature prediction calculation in a timely manner, thereby enabling highly accurate temperature prediction. Is possible.
According to the fifth aspect, the reliability of the image forming apparatus is improved by extending the life of the fixing device as compared with the conventional one.
According to the sixth aspect, it is possible to realize control that minimizes the temperature difference in the heating member, and to reduce the occurrence of partial overheating during heating of the heating member.
According to the seventh aspect, since it is possible to perform high-speed and high-precision control as compared with control based on temperature detection by a conventional sensor, it is possible to suppress deterioration of the heating member.
According to the eighth aspect, it is possible to realize control that minimizes the temperature difference in the heating member, and to reduce the occurrence of partial overheating during heating of the heating member.
According to the ninth aspect, it is possible to detect the deterioration of the heating member more accurately than in the past.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram of an image forming apparatus having an image fixing apparatus according to the present embodiment. The image forming apparatus shown in FIG. 1 is a so-called tandem type image forming apparatus, for example, a plurality of image forming units 10 (10Y, 10M, 10C, 10K) on which toner images of respective color components are formed by electrophotography. And an endless intermediate transfer belt (toner image holder) 15 for sequentially transferring (primary transfer) and holding each color component toner image formed by each image forming unit 10, and transferring the toner image onto the intermediate transfer belt 15. A secondary transfer device (transfer device) 20 that collectively transfers (secondary transfer) the superimposed images to a sheet as a transfer material, and a fixing device (fixer) 41 that fixes the secondary transferred image on the sheet; It is equipped with. Moreover, it has the control part 40 which controls operation | movement of each apparatus (each part).

  In the present embodiment, each image forming unit 10 (10Y, 10M, 10C, 10K) includes an electrophotographic device around a photosensitive drum (image holding body) 11Y, 11M, 11C, 11K that rotates in the direction of arrow A. Is arranged. That is, the charger 12 that charges the photosensitive drums 11Y, 11M, 11C, and 11K, and the laser exposure unit 13 that writes an electrostatic latent image on the photosensitive drums 11Y, 11M, 11C, and 11K (FIG. 1). And a developing device 14 that accommodates each color component toner and visualizes the electrostatic latent images on the photosensitive drums 11Y, 11M, 11C, and 11K with the toner. Has been. Further, the primary transfer roll 16 that transfers the color component toner images formed on the photosensitive drums 11Y, 11M, 11C, and 11K to the intermediate transfer belt 15, and the residual toner on the photosensitive drums 11Y, 11M, 11C, and 11K A drum cleaner 17 to be removed is disposed. These image forming units 10 are arranged in the order of yellow (Y color), magenta (M color), cyan (C color), and black (K color) from the upstream side of the intermediate transfer belt 15.

  The intermediate transfer belt 15 as an intermediate transfer member is a film-like endless belt in which an appropriate amount of a conductive agent such as carbon black is contained in a resin such as polyimide or polyamide. The intermediate transfer belt 15 can be circulated and rotated (rotated) at a predetermined speed in the direction of arrow B shown in FIG. 1 by various rolls. As these various rolls, there are provided a drive roll 31 that is driven by a motor (not shown) to rotate the intermediate transfer belt 15 and a function of giving a constant tension to the intermediate transfer belt 15 and preventing meandering of the intermediate transfer belt 15. Tension roll 32. As other various rolls, there are a driven roll 33 that supports the intermediate transfer belt 15 and applies a constant tension, and a backup roll (support roll) 22 provided in a secondary transfer portion.

  In the intermediate transfer module 18 provided to face the photosensitive drums 11Y, 11M, 11C, and 11K, each primary transfer roll 16 provided inside the intermediate transfer belt 15 that extends substantially linearly has a charging polarity of toner. A voltage with the opposite polarity is applied. Thus, the toner images on the respective photosensitive drums 11Y, 11M, 11C, and 11K are sequentially electrostatically attracted to the intermediate transfer belt 15, and a superimposed toner image is formed on the intermediate transfer belt 15. .

  The secondary transfer device 20 includes a secondary transfer roll 21 disposed on the toner image holding surface side of the intermediate transfer belt 15 and a backup roll 22 as an opposite roll. That is, the secondary transfer roll 21 is disposed in pressure contact with the backup roll 22 with the intermediate transfer belt 15 interposed therebetween. By the secondary transfer device 20 configured as described above, the visible image that has been multiplex-transferred onto the intermediate transfer belt 15 is transferred onto a sheet conveyed from a sheet tray 35 described later.

  A belt cleaner 34 that removes residual toner and paper dust on the intermediate transfer belt 15 after the secondary transfer and cleans the surface of the intermediate transfer belt 15 is provided on the downstream side of the backup roll 22.

A paper tray 35 for storing paper is provided on the upstream side of the secondary transfer position, and a fixing device 41 is provided on the downstream side of the secondary transfer position. Then, the sheets stacked on the sheet tray 35 are taken out at a predetermined timing, conveyed to a secondary transfer position by the secondary transfer device 20 and secondarily transferred, and then conveyed to the fixing device 41.
Here, the fixing device 41 includes a heating roll (heating member) 42, a halogen lamp (heat generation source, heating source) 43 built in the heating roll 42, and a pressure roll (pressure application) disposed opposite to the heating roll 42. Member) 44. Details will be described later.

  Next, a basic image forming process of the image forming apparatus according to the present embodiment will be described. Image data output from an image reading device (not shown) or a personal computer (PC) (not shown) is input to the image forming apparatus shown in FIG. In the image forming apparatus, after predetermined image processing is performed by an image processing apparatus (not shown), an image forming operation is performed by the image forming unit 10 or the like. In the image processing apparatus, the input reflectance data is subjected to image processing such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame deletion, color editing, and movement editing. The image data subjected to the image processing is converted into color material gradation data of four colors of yellow (Y), magenta (M), cyan (C), and black (K), and is output to the laser exposure unit 13. .

In the laser exposure device 13, for example, an exposure beam Bm emitted from a semiconductor laser is applied to the photosensitive drums 11Y, 11M, 11C of the image forming units 10Y, 10M, 10C, 10K according to the input color material gradation data. , 11K. In the photosensitive drums 11Y, 11M, 11C, and 11K of the image forming units 10Y, 10M, 10C, and 10K, the surface is charged by the charger 12, and then the surface is scanned and exposed by the laser exposure unit 13, thereby electrostatic latent images. Is formed. The formed electrostatic latent image is developed as a toner image of each color of yellow, magenta, cyan, and black in each of the image forming units 10Y, 10M, 10C, and 10K.
The toner images formed on the photosensitive drums 11Y, 11M, 11C, and 11K of the image forming units 10Y, 10M, 10C, and 10K are in contact with the photosensitive drums 11Y, 11M, 11C, and 11K and the intermediate transfer belt 15. The image is transferred onto the intermediate transfer belt 15 at the primary transfer portion. More specifically, in the primary transfer portion, the primary transfer roll 16 applies a voltage having a polarity opposite to the charged polarity of the toner to the base material of the intermediate transfer belt 15, and the unfixed toner image is transferred to the surface of the intermediate transfer belt 15. Are sequentially superposed on each other to perform primary transfer. The unfixed toner image primarily transferred in this way is conveyed to the secondary transfer device 20 as the intermediate transfer belt 15 rotates.

In the secondary transfer device 20, the secondary transfer roll 21 is pressed against the backup roll 22 in a state where the intermediate transfer belt 15 is sandwiched therebetween in accordance with the timing of the secondary transfer onto the paper. At this time, the sheet conveyed in time is sandwiched between the intermediate transfer belt 15 and the secondary transfer roll 21. An unfixed toner held on the intermediate transfer belt 15 at a secondary transfer position where a transfer electric field is formed as a counter electrode on the secondary transfer roll 21 and is pressed by the secondary transfer roll 21 and the backup roll 22. The image is electrostatically transferred to the paper.
Thereafter, the sheet on which the toner image has been electrostatically transferred is conveyed as it is while being peeled off from the intermediate transfer belt 15 by the secondary transfer roll 21. Then, the speed is changed in accordance with the optimum conveyance speed in the fixing device 41, and the paper is conveyed to the fixing device 41. The unfixed toner image on the sheet is fixed on the sheet by being subjected to a fixing process by heat and pressure by the fixing device 41. The paper on which the fixed image is formed is discharged to the outside of the apparatus by a discharge roll (not shown).
On the other hand, after the transfer to the paper is completed, the residual toner remaining on the intermediate transfer belt 15 is conveyed to the cleaning unit as the intermediate transfer belt 15 rotates, and is removed from the intermediate transfer belt 15 by the belt cleaner 34. Is done.

FIG. 2 is a cross-sectional view of the heating roll 42, the halogen lamp 43, and the pressure roll 44 that constitute the fixing device 41.
As shown in FIG. 2, the heating roll 42 of the fixing device 41 includes a core layer (base material) 42r such as iron or aluminum, an elastic layer 42c such as silicon rubber covering the core layer 42r, and the center of the core layer 42r. And a halogen lamp (heat source) 43 for heating provided in the section. The pressure roll 44 includes a core layer 44r and an elastic layer 44c that covers the core layer 44r.
The elastic layer 42c of the heating roll 42 can be further covered with a release layer (not shown), and the elastic layer 44c of the pressure roll 44 is further covered with a release layer (not shown). Can do. Moreover, although the heating roll 42 is what is called a soft roll which has the elastic layer 42c, it can also be comprised by what is called a hard roll which does not have the elastic layer 42c. It is also conceivable to provide the pressure roll 44 with a halogen lamp 43 provided in the heating roll 42.

  The heating roll 42 and the pressure roll 44 thus configured have the following operation. That is, the conveyed paper is pressed against the heating roll 42 by the pressure roll 44 at a pressure of 0.1 to 0.8 MPa, for example. Then, the toner resin of the toner image held on the front side of the paper is heated and melted and fixed on the paper. In the present embodiment, the fixing device 41 is configured by using the heating roll 42 and the pressure roll 44, but other configurations, for example, a configuration in which a belt is stretched around the roll may be employed. .

FIG. 3 is a schematic diagram for explaining the support structure of the heating roll 42.
As shown in FIG. 3, each end of the heating roll 42 is supported by support bodies (holding members) 45 and 46, and is thereby installed as a part of the fixing device 41. The supports 45 and 46 are made of a metal such as iron or aluminum, for example.

4 and 5 are explanatory diagrams of the halogen lamps 43a and 43b built in the heating roll 42. FIG. Specifically, FIG. 4A is a schematic diagram for explaining the configuration of the halogen lamps 43a and 43b, FIG. 4B is a graph showing a heat generation distribution by the halogen lamp 43a, and FIG. These are graphs showing the heat generation distribution by the halogen lamp 43b. Moreover, (a)-(f) of FIG. 5 is a graph which shows the heat_generation | fever distribution by the combination of the halogen lamps 43a and 43b. In each graph, the vertical axis represents the calorific value (W), and the horizontal axis represents the separation distance (mm) from one end of the heating roll 42. Here, the heat generation distribution refers to a value representing the emission intensity, and is expressed as a relative value with respect to the entire wattage of the halogen lamp 43a or the halogen lamp 43b. That is, when the light emission distribution is integrated in the axial direction (the horizontal axis direction of the graph), the total wattage is obtained.
As shown in FIG. 4A, the heating roll 42 includes two halogen lamps 43 a and 43 b inside as the halogen lamp 43. The two halogen lamps 43a and 43b have different light distributions. That is, the halogen lamp 43a is provided with light emitting portions at both ends (each end) in the axial direction of the heating roll 42, and the halogen lamp 43b is sandwiched between the central portions (both ends) of the heating roll 42. A light emitting portion is arranged in an intermediate portion in the axial direction. Therefore, the halogen lamp 43a heats each end of the heating roll 42 as shown in FIG. 4B, and the halogen lamp 43b is connected to the heating roll 42 as shown in FIG. The middle part is heated. In other words, each end of the heating roll 42 is mainly heated by the halogen lamp 43a, and an intermediate portion of the heating roll 42 is mainly heated by the halogen lamp 43b. With such a configuration, the heating region R is formed in the heating roll 42.

  These halogen lamps 43a and 43b are heated and controlled by the control unit 40 (see FIG. 1). That is, the control unit 40 controls the heating state so that the heating roll 42 is heated by the halogen lamp 43a and is also heated by the halogen lamp 43b.

  The halogen lamps 43a and 43b are controlled by the control unit 40 so as to change the energy ratio between them. That is, the control unit 40 performs control so as to change the relative amount of heat generated between the halogen lamp 43a and the halogen lamp 43b. Accordingly, the ratio of the amount of heat supplied at each end of the heating roll 42 and the amount of heat supplied at the intermediate portion can be changed. Details thereof will be described later.

  In the present embodiment, as described above, the heating roll 42 is controlled to be heated by both the halogen lamps 43a and 43b, but the heating roll 42 is controlled by one of the halogen lamp 43a and the halogen lamp 43b. It is also possible to control the heating. In this embodiment, the halogen lamp 43 is composed of two halogen lamps 43a and 43b. However, it is also conceivable that the halogen lamp 43 is composed of another number of halogen lamps, for example, one or three.

  The heat generation distribution (light emission pattern, heat distribution pattern) shown in FIG. 5A is the case where the halogen lamp 43a and the halogen lamp 43b are 1: 1 (A pattern), and the heat generation shown in FIG. The distribution is when the halogen lamp 43a and the halogen lamp 43b are 0.5: 0.5 (B pattern). In this way, when heating is performed over the entire region of each end and intermediate portion of the heating roll 42, the amount of heat generated can be changed.

  Further, the heat generation distribution shown in (c) of FIG. 5 is the case where the halogen lamp 43a and the halogen lamp 43b are 1: 0.5 (C pattern). In the heat generation distribution shown in (d) of FIG. : 0.2 (D pattern). Further, the heat generation distribution shown in (e) of the figure is the case where the halogen lamp 43a and the halogen lamp 43b are 0.5: 1 (E pattern), and the heat generation distribution shown in (f) of the same figure is 0. .2: 1 (F pattern). Thus, it is comprised so that the emitted-heat amount can be changed with each edge part of the heating roll 42, and an intermediate part.

FIG. 6 is a block diagram illustrating a configuration of the fixing device 41.
As shown in FIG. 6, the fixing device 41 includes a temperature detection unit (temperature detection means) 47 that detects the surface temperature of the heating roll 42, and a halogen lamp 43 (halogen lamps 43a and 43b shown in FIG. 4A). And a power detection unit 49 that detects a voltage and a current (power) supplied from the power supply 48 to the halogen lamp 43. The fixing device 41 controls the output of the power supply 48 based on the calculation result of the storage unit 50 that stores various information, the calculation unit 51 that performs prediction calculation of the surface temperature distribution of the heating roll 42, and the calculation unit 51. And a heating control unit 52 that performs. In addition, the fixing device 41 includes a time measuring unit (timer) 53 that measures an elapsed time since the main power source (not shown) of the image forming apparatus is turned off, and a deterioration detecting unit (deteriorating the heating roll 42). Degradation detection means) 54. The calculation unit 51 and the heating control unit 52 can constitute a prediction unit. Further, the heating control unit 52 can constitute a determining means.

  The temperature detector 47 detects surface temperatures at a plurality of different locations in the axial direction of the heating roll 42. Specifically, the temperature detector 47 detects the surface temperature of the central portion in the axial direction and detects the surface temperature of one end portion in the axial direction. The surface temperature referred to here is the same as the initial temperature or the ambient temperature. The temperature detection unit 47 transmits the detected surface temperature to the calculation unit 51 and the deterioration detection unit 54.

  The power supply 48 supplies power to the halogen lamps 43a and 43b based on the control of the heating control unit 52. Specifically, the power supply 48 receives an instruction about the amount of power supplied and the supply time of each of the halogen lamps 43a and 43b from the heating control unit 52, and supplies power to the halogen lamps 43a and 43b according to the instruction.

  The power detection unit 49 detects the voltage and current supplied from the power supply 48 to the halogen lamp 43a, detects the voltage and current supplied from the power supply 48 to the halogen lamp 43b, and transmits the detection result to the calculation unit 51. .

The storage unit 50 stores various information necessary for the calculation unit 51 to perform prediction calculation. That is, the storage unit 50 stores the material, thickness (layer thickness), and length of the core layer 42r (see FIG. 2) and the elastic layer 42c (see FIG. 2) of the heating roll 42, as well as the heat capacity and thermal conductivity. Remember. When specifically enumerated an example thereof, for example, the cross-sectional area A _r of the core layer 42r (m ²⁾ and the thermal conductivity ^{_{λ r (W / m 3 ·}} K) and cross-sectional area A _c and the thermal conductivity of the elastic layer 42c λ _c . Further, the surface area A _in of the inner peripheral surface of the core layer 42r and the surface area A _out of the outer peripheral surface of the elastic layer 42c.
In addition, the storage unit 50 stores the heat distribution of each of the halogen lamps 43a and 43b (see (b) and (c) of FIG. 4). That is, the amount of heat generated at each point in the axial direction of the halogen lamps 43a and 43b is acquired and stored in advance.
In addition, the storage unit 50 stores heat dissipation conditions for the surface and inside of the heating roll 42 and heat dissipation conditions for the supports 45 and 46. When specifically enumerated an example thereof, the heat transfer coefficient ^{_{α in (W / m 2 ·}} K) from the inner peripheral surface of the core layer 42r to air, heat transfer coefficient from the outer peripheral surface of the elastic layer 42c to the air alpha _out ( W / m ² · K) and the heat transfer coefficient α _s from the core layer 42 _r to the supports 45 and 46.

  The calculation unit 51 performs a predetermined calculation using the surface temperature detected by the temperature detection unit 47, the detection result by the power detection unit 49, and the information stored in the storage unit 50, whereby the heating roll The surface temperature distribution in the axial direction of 42 is calculated. The surface temperature distribution calculated by the calculation unit 51 is transmitted to the heating control unit 52 and the deterioration detection unit 54. In the present embodiment, a configuration for predicting the surface temperature distribution is adopted. Specific calculation will be described later.

  The heating control unit 52 determines a control pattern for the halogen lamps 43 a and 43 b based on the surface temperature distribution calculated by the calculation unit 51. That is, the heating control unit 52 determines the lighting time and light emission intensity of the halogen lamps 43 a and 43 b using the surface temperature distribution predicted by the calculation unit 51. And the heating control part 52 controls the output of the power supply 48 according to the determined control pattern.

  The timer 53 measures the elapsed time from the main power-off of the image forming apparatus and outputs the elapsed time information to the heating controller 52 as elapsed time information. The elapsed time measured by the time measuring unit 53 is used for the heating control unit 52 to predict the detailed state when the main power source of the image forming apparatus is turned on.

  The deterioration detector 54 detects deterioration of the heating roll 42 using the surface temperature detected by the temperature detector 47 and the surface temperature distribution calculated by the calculator 51. That is, the deterioration detection unit 54 estimates the deterioration state of the elastic layer 42 c of the heating roll 42 based on the error between the actual surface temperature by the temperature detection unit 47 and the predicted value by the calculation unit 51. When detecting the deterioration of the elastic layer 42c, the deterioration detection unit 54 instructs the storage unit 50 to rewrite information stored in advance in the storage unit 50, for example, a control pattern.

FIG. 7 is a flowchart showing a processing procedure after the main power supply of the image forming apparatus is turned on. Each of (a) to (c) of FIG. 8 is a graph showing a predicted temperature distribution in the axial direction of the heating roll 42 (see FIG. 6) of the fixing device 41, where the vertical axis represents temperature (° C.) and the horizontal axis represents. Roll axis direction position (mm).
In the flowchart shown in FIG. 7, when the control unit 40 (see FIG. 1) detects that the main power supply (not shown) of the image forming apparatus is turned on (power on) (step 101), the heating control unit 52 (see FIG. 6). ) Obtains elapsed time information from the last main power-off from the timer 53 (see FIG. 6) (step 102), and whether or not a predetermined time has passed in order to grasp the initial state of the image forming apparatus. Is determined (step 103). That is, the heating control unit 52 determines whether or not the surface temperature of the heating roll 42 of the fixing device 41 has been lowered to room temperature. Specifically, if a sufficient time for cooling the heating roll 42 has elapsed, the process proceeds to step 104 to perform a processing procedure for predictive control, and on the other hand, if such a time has not elapsed, The processing procedure in FIG. 7 ends.

  If it adds about step 103, when the heating control part 52 judges that sufficient time for cooling of the heating roll 42 has passed, the temperature detection part 47 will transmit the detected temperature to the calculating part 51 as temperature information. Moreover, the power detection unit 49 (see FIG. 6) transmits the detected power to the calculation unit 51 as power information. Then, the process proceeds to Step 104. When a sufficient time has passed for cooling the heating roll 42, it is predicted that the temperature at each position in the axial direction of the heating roll 42 is substantially uniform, as shown in FIG. It is a premise of calculation.

  Thus, the calculating part 51 acquires temperature information and electric power information from the temperature detection part 47 and the electric power detection part 49 as information required for a prediction calculation (step 104). Moreover, the calculating part 51 acquires by reading the other information required for prediction calculation from the memory | storage part 50 (step 104). Thereafter, the calculation unit 51 performs prediction calculation for control (temperature prediction control) for predicting the surface temperature of the heating roll 42 using the temperature of the heating roll 42 as an initial temperature (step 105).

Here, the calculation of the temperature prediction in step 105 will be described.
FIG. 9 is a diagram for explaining a temperature prediction model of the heating roll 42, and schematically shows a cross-sectional view cut along the axial direction of the heating roll 42.
The temperature prediction model shown in FIG. 9 divides the heating roll 42 into n cells along the axial direction. The cell width (division width) is dx. The temperature at a certain position i (i = 1 to n) is T _i , the elastic layer 42c and the core layer 42r have no temperature distribution in the thickness direction, and the temperature in each cell is uniform. FIG. 9 illustrates the amount of heat q1 entering and exiting due to the axial heat conduction in the elastic layer 42c of the heating roll 42 and the amount of heat q2 entering and exiting due to the axial heat conduction in the core layer 42r of the heating roll 42. In FIG. 9, the amount of heat q3 moving from the inner surface of the heating roll 42 (the inner peripheral surface of the core layer 42r) to the air, and the amount of heat q4 moving from the surface of the heating roll 42 (the outer peripheral surface of the elastic layer 42c) to the air. Are shown. In FIG. 9, the amount of heat q5 transferred from the core layer 42 r of the heating roll 42 to the support 45, the amount of heat q6 transferred from the core layer 42 r of the heating roll 42 to the support 46, and the heating roll 42 by the halogen lamp 43. The lamp calorific value q _lamp supplied to is shown.

A method for obtaining the surface temperature T _i of the cell at the position i = 2 to n−1 will be described with reference to FIG. 9. The surface temperatures T _i−1 and T _{i + 1} are the surface temperatures of other cells adjacent to the cell at the position i.
The amount of heat q1 entering and exiting the elastic layer 42c by axial heat conduction is calculated from the cross-sectional area A _c and the thermal conductivity λ _c .

とし、コア層４２ｒで軸方向熱伝導により出入りする熱量ｑ２を、断面積Ａ_r、熱伝導率λ_rから、

And the amount of heat q2 entering and exiting the core layer 42r by axial heat conduction is calculated from the cross-sectional area A _r and the thermal conductivity λ _r .

とする。

And

Further, the amount of heat q3 to move from the inner surface (inner peripheral surface of the core layer 42r) to the air of the heating roll 42, the heat transfer coefficient alpha _in to the surface area A _in and internal air,

とし、加熱ロール４２の表面（弾性層４２ｃの外周面）から空気へ移動する熱量ｑ４を、表面積Ａ_out及び外部空気への熱伝達係数α_outから、

And the amount of heat q4 transferred from the surface of the heating roll 42 (the outer peripheral surface of the elastic layer 42c) to the air, from the surface area A _out and the heat transfer coefficient α _out to the external air,

とする。なお、Ｔ_airは外気温度である。

And Note that T _air is the outside air temperature.

And if the lamp calorific value supplied to the heating roll 42 is q _lamp , the heat quantity Q of the total heat balance of the heating roll 42 is expressed by the above equations 1 to 4.

である。なお、ランプ発熱量ｑ_lampは、供給される電流と電圧とが電力検出部４９により検知され、その検出結果から供給電力量として算出されるものである。

It is. Note that the lamp heat generation amount q _lamp is calculated as a supply power amount from the detection result of the supplied current and voltage detected by the power detection unit 49.

On the other hand, when the cell temperature changes by dT (K) at a certain time dt (seconds), the heat quantity Q (W) accumulated in the cell is equal to the heat capacities C (J / m) of the elastic layer 42c and the core layer 42r. ³ · K), the volume V _c of the elastic layer 42c, and the volume V _{r of the} core layer 42r,

である。そこで、式５及び式６より微分方程式

It is. Therefore, the differential equation is obtained from Equation 5 and Equation 6.

を解いて、加熱ロール４２の位置ｉ＝２〜ｎ−１における各セルの表面温度Ｔ_iを予測する。

And the surface temperature T _i of each cell at the position i = 2 to n−1 of the heating roll 42 is predicted.

Next, how to obtain the surface temperatures T ₁ and T _n of the cells at positions i = 1 and n at both ends of the heating roll 42 will be described. The surface temperatures T ₁ and T _n need to be predicted by a formula different from the case of the positions i = 2 to n−1 in order to consider the heat transfer to the supports 45 and 46. It is assumed that only the core layer 42 r of the heating roll 42 is in contact with the supports 45 and 46.

The amount of heat q5 transferred to the support 45 is _{calculated from} the heat transfer coefficient α _s45 to the support 45, the roll cross-sectional area A _c , and the temperature _Th 45 of the support 45.

とし、加熱ロール４２の内部の熱伝導ｑ１'は、

And the heat conduction q1 ′ inside the heating roll 42 is

とする。なお、式９には、弾性層４２ｃの熱伝導が含まれていない。

And Note that Equation 9 does not include the heat conduction of the elastic layer 42c.

  When the cell temperature changes by dT (K) at a certain time dt (seconds), the amount of heat Q (W) stored in this cell is

として、式１０と式３，式４，式８及び式９とから微分方程式

From Equation 10, Equation 3, Equation 4, Equation 8, and Equation 9, the differential equation

を解いて位置ｉ＝１のセルの表面温度Ｔ₁を予測する。

To predict the surface temperature T ₁ of the cell at position i = 1.

Similarly, the amount of heat q6 transferred to the support 46 is calculated from the heat transfer coefficient α _s46 to the support 46, the roll cross-sectional area A _c , and the temperature T _{h46 of the} support 46.

とし、加熱ロール４２の内部の熱伝導ｑ１''は、

And the heat conduction q1 ″ inside the heating roll 42 is

として、式１０と式３，式４，式１２及び式１３から微分方程式

From Equation 10, Equation 3, Equation 4, Equation 12, and Equation 13, the differential equation

を解いて位置ｉ＝ｎのセルの表面温度Ｔ_nを予測する。なお、式１３には、弾性層４２ｃの熱伝導が含まれていない。

To predict the surface temperature T _n of the cell at position i = n. Note that Equation 13 does not include the heat conduction of the elastic layer 42c.

  In addition, in the present embodiment, a heat dissipation coefficient (heat transfer coefficient α) is stored in advance, and temperature prediction is performed by simultaneously solving the movement of heat to the outside air and the movement of heat to both ends (heat radiation). Is. That is, in the present embodiment, regarding the movement of heat quantity to the outside air and the movement of heat to both ends, the temperature distribution obtained from the heat conduction and the lamp heat is not corrected by inputting measured data.

Returning to FIG. 7, the description of the processing procedure will be continued.
The calculation unit 51 obtains the maximum axial temperature difference (axial temperature unevenness) Δt (see FIG. 8B) based on the calculation result in step 105, and transmits it to the heating control unit 52. Then, the heating control unit 52 determines whether or not the surface temperature of the heating roll 42 is uneven in the axial direction (step 106). That is, the heating control unit 52 determines whether the maximum temperature difference Δt acquired from the calculation unit 51 is equal to or less than an allowable value. The allowable value used here is stored in advance in the storage unit 50, and the heating control unit 52 acquires the allowable value by reading from the storage unit 50.

  When it is determined in step 106 that the maximum temperature difference Δt is equal to or less than the allowable value and there is no temperature unevenness, the heating control unit 52 proceeds to step 110, and if the maximum temperature difference Δt exceeds the allowable value and there is temperature unevenness. When it is determined, the control method is determined (step 107), and the process proceeds to a warm-up operation described later.

The determination of the control method in step 107 will be further described. Matters for which the control method is determined are lighting time and heat distribution pattern.
In determining the lighting time, one or a plurality of patterns are selected from the heat distribution combination patterns, and the lighting time of each pattern is determined. To explain with an example, the allowable value used for determining whether or not there is temperature unevenness is 10 ° C., and the allowable value of the warm-up time until the temperature detected by the temperature detection unit 47 reaches 160 ° C. (time loss allowable value) Is 25 seconds-1 seconds. Therefore, it is necessary for the control unit 40 to perform control so as to be within these two allowable values during warm-up when the power is turned on.

  It is assumed that the heating control unit 52 predicts the temperature and time when the power is turned on in a certain temperature / power state as follows. That is, the selected heat generation distribution is predicted to have a predicted warm-up time of 25 seconds and a predicted temperature difference of 20 degrees when the A pattern shown in FIG. 5A is set as the default. And This prediction result indicates that the maximum temperature difference Δt, which is the predicted temperature difference, exceeds the allowable value of 10 ° C., and the determination is “x”, so the control method needs to be changed. Therefore, the heating control unit 52 extracts heat generation distribution candidates. For extraction of candidates, an extraction algorithm is stored in advance in the storage unit 50 (see FIG. 6), and is read out as necessary.

  Suppose that A pattern and E pattern are extracted as candidate I, and A pattern and F pattern are extracted as candidate II. In the case of this example, if the A pattern having the maximum power is preferentially used from the stored A pattern to the F turn, and the temperature at both ends is high Therefore, an E pattern or an F pattern with low heat distribution at both ends is extracted as a candidate.

FIG. 10 is a table showing the results of temperature prediction with the lighting time of the heat distribution pattern changed for candidate I and candidate II. In the case of candidate I and candidate II described above, the heating control unit 52 performs the temperature prediction by changing the lighting time of the heat distribution pattern with the candidates I and II, thereby obtaining the result shown in FIG. Using this result, the temperature difference and the loss time are determined, and both within the allowable values (optimum pattern) are adopted as the control method. That is, the case where the overall determination is “◯” is a candidate II a, and specifically, a control method in which the lighting time of the A pattern is 15 seconds and the lighting time of the F pattern is 10.2 seconds. According to this control method, the time delay allowable value from the preset warm-up time is −0.2 seconds, and the maximum temperature difference Δt is 5.7 ° C., both of which are within the allowable value range. Is within.
In this embodiment, there is only one control method with a comprehensive judgment of “O”. However, if there are a plurality of control methods with an overall judgment of “O”, the power consumption is low or the time is lost. It is conceivable to use one with less.

  Returning to FIG. 7, the warm-up operation performed after the control method is determined in step 107 will be described. First, the heating control unit 52 starts lighting the halogen lamp 43 (step 108), and performs the control (step 109). Such control is performed based on the determined lighting time and heat distribution pattern without performing temperature detection. Also, such control is realized by power cutoff control (duty cycle change) to the halogen lamp 43.

  Then, when the heating control unit 52 is lit for the lighting time determined by the determined heat distribution pattern, the heating control unit 52 ends the warm-up operation and sets the ready state (step 110). More specifically, first, the A pattern is lit for 15 seconds, then the F pattern is switched to 10.2 seconds and then ready.

  Then, the temperature detection unit 47 detects the temperature of the surface of the heating roll 42 (step 111), and transmits the detected temperature to the deterioration detection unit 54. The deterioration detection unit 54 causes the calculation unit to calculate the difference between the detected temperature and the predicted temperature by the heating control unit 52, and determines the presence or absence of deterioration based on the calculation result. That is, the deterioration detector 54 detects the deterioration of the heating roll 42 based on the difference between the detected temperature and the predicted temperature.

  More specifically, the surface of the heating roll 42 is heated to a predetermined temperature by the control by the heating control unit 52. However, if the layer thickness change of the elastic layer 42c of the heating roll 42 occurs due to deterioration due to long-term use, an error occurs between the predicted temperature by the heating control unit 52 and the temperature detected by the temperature detection unit 47. Such an error reduces the accuracy of predictive control. Therefore, the deterioration detection unit 54 determines whether or not to correct the layer thickness information of the elastic layer 42c of the heating roll 42 based on the difference between the predicted temperature and the detected temperature (step 112).

  When determining that the layer thickness information needs to be corrected, the deterioration detection unit 54 calculates the layer thickness of the elastic layer 42c based on the detected temperature. Then, the deterioration detection unit 54 performs information correction by rewriting the layer thickness of the elastic layer 42c stored in the storage unit 50 (step 113). In addition, in the next prediction control, a temperature prediction calculation is performed using the rewritten information.

  The correction of the layer thickness information will be specifically described. As shown in FIG. 8C, the detected temperature is higher than the predicted temperature, so that the deterioration detection unit 54 can detect the elastic layer 42c. It can be detected that the layer thickness has decreased. When the deterioration detection unit 54 determines that the correction of the layer thickness of the elastic layer 42c is necessary, the deterioration detection unit 54 causes the calculation unit 51 to calculate the layer thickness of the elastic layer 42c based on the detected temperature.

FIG. 11 shows a comparison between the temperature distribution in the ready state when the warm-up control according to the present embodiment is performed (after optimization) and the temperature distribution in the ready state without the warm-up control (no control). The vertical axis represents temperature (° C.), and the horizontal axis represents the position (mm) in the axial direction of the heating roll 42.
As shown in FIG. 11, at both ends of the paper passing area P with the heating roll 42, a more uniform temperature distribution in the ready state is obtained after the optimization shown by the solid line than when there is no control shown by the one-dot chain line. Become. The temperature unevenness falls within the allowable range when the temperature allowable value is, for example, 10 ° C. or less. On the other hand, outside the sheet passing area P, the temperature rise of the heating roll 42 is suppressed, and it is possible to efficiently use power.
More specifically, for example, when the two halogen lamps 43a and 43b are turned on simultaneously with the rated power, when the ready state is reached in about 25 seconds, the ready state is switched by switching between (a) and (f) in FIG. The temperature unevenness is eliminated, and the loss of warm-up time due to switching is about 0.2 seconds.

FIG. 12 is a graph for explaining a difference in warm-up control due to a difference in supply power, where the vertical axis represents the surface temperature (° C.) of the heating roll 42 and the horizontal axis represents the elapsed time (seconds). The broken line in FIG. 12 indicates the case of rated power (rated current), the solid line indicates the case where the power variation is + 10%, and the alternate long and short dash line indicates the case where the power variation is −10%.
As shown in FIG. 12, the time change of the temperature rise greatly changes due to the difference in the supplied power. For example, if the surface temperature reaches 160 ° C., the ready state is reached, and at the rated power, the ready state is reached in about 25 seconds. For this reason, it is conceivable that the temperature reaches an unnecessarily high temperature especially when the power variation is + 10%. Therefore, when the control is performed at each optimum timing and heat distribution pattern, a stable ready temperature can be ensured regardless of environmental fluctuations. As described above, it is possible to reduce overheating by selecting optimal control, and it is possible to extend the life of the heating roll 42.

FIG. 13 is a graph for explaining the correction of the prediction error due to the layer thickness deterioration of the elastic layer 42 c of the heating roll 42, where the vertical axis is the temperature (° C.) and the horizontal axis is the axial position (mm) of the heating roll 42. is there.
The solid line shown in FIG. 13 is the predicted temperature distribution in the initial state of the heating roll 42. Compared with the case where the elastic layer 42c is deteriorated and the layer thickness is reduced by 5% (shown by a broken line), the elastic layer 42c. A prediction error due to layer thickness degradation occurs. Then, by performing the information correction in step 113 in FIG. 7, highly accurate predictive control according to the layer thickness can be performed.

1 is a schematic configuration diagram of an image forming apparatus having an image fixing device according to the present embodiment. It is a cross-sectional view of a heating roll, a halogen lamp, and a pressure roll constituting the fixing device. It is the schematic explaining the support structure of a heating roll. (A) is the schematic for demonstrating the structure of a halogen lamp, (b) And (c) is a graph which shows the heat_generation | fever distribution by a halogen lamp. (A)-(f) is a graph which shows the heat_generation | fever distribution by the combination of a halogen lamp. FIG. 2 is a block diagram illustrating a configuration of a fixing device. 6 is a flowchart illustrating a processing procedure after the main power supply of the image forming apparatus is turned on. (A)-(c) is a graph which shows the estimated temperature distribution in the axial direction of the heating roll of a fixing device. It is a figure for demonstrating the temperature prediction model of a heating roll. It is a table | surface which shows the result of the temperature prediction which changed the lighting time of the heat distribution pattern about candidate I and candidate II. 6 is a graph showing a comparison between a temperature distribution in a ready state when warm-up control according to the present embodiment is performed (after optimization) and a temperature distribution in a ready state without warm-up control (without control). . It is a graph explaining the difference of warm-up control by supply power difference. It is a graph explaining correction | amendment of the prediction error by the layer thickness degradation of the elastic layer of a heating roll.

Explanation of symbols

DESCRIPTION OF SYMBOLS 40 ... Control part, 41 ... Fixing device, 42 ... Heating roll, 42c, 44c ... Elastic layer, 42r, 44r ... Core layer, 43, 43a, 43b ... Halogen lamp, 44 ... Pressure roll, 45, 46 ... Support , 47 ... temperature detection unit, 48 ... power supply, 49 ... power detection unit, 50 ... storage unit, 51 ... calculation unit, 52 ... heating control unit, 53 ... timing unit, 54 ... deterioration detection unit

Claims (9)

A heat source capable of switching between a plurality of different heat generation distributions;
A heating member having a heating area of a predetermined width heated by the heat source;
A pressure member provided opposite to the heating member and fixing the toner image transferred to the paper to the paper together with the heating member;
Predicting means for predicting a temperature distribution of the heating region of the heating member after heating by the heat source by a predetermined calculation when heating of the heating member by the heat source is started;
Based on the prediction result by the prediction means, one or a plurality of heat generation distributions used for heating the heating member from the plurality of heat generation distributions of the heat generation source and a heating time in the one or more heat generation distributions, Determining means for determining a temperature difference in the heating region of the heating member to be a predetermined value or less;
Including an image fixing device.   The determining means sets the one or a plurality of heat generation distributions and the heating time to a predetermined time until the temperature difference in the heating region of the heating member becomes a predetermined value or less and is heated to a fixable state. The image fixing device according to claim 1, wherein the image fixing device is determined to be within a range.   The predetermined calculation by the predicting means includes information on the plurality of heat generation distributions of the heat source, information on heat conduction in the width direction of the heating member, information on heat transfer from the heating member to ambient air, and the heating member. 2. The image fixing apparatus according to claim 1, wherein the calculation is performed using information on heat transfer from the heat to a holding member that holds the heating member. Temperature detecting means for detecting the surface temperature of the heating member in a fixable state;
A deterioration detection means for calculating a difference between a prediction result by the prediction means and a detection result by the temperature detection means to detect deterioration of the heating member;
The image fixing apparatus according to claim 1, further comprising: An image carrier,
A transfer device for transferring the toner image held on the image carrier to a recording medium;
A fixing device for fixing the toner image transferred by the transfer device to a recording medium;
Including
The fixing device includes:
A heat source capable of switching between a plurality of different heat generation distributions;
A heating member having a heating area of a predetermined width heated by the heat source;
A pressure member provided opposite to the heating member and fixing the toner image transferred to the paper to the paper together with the heating member;
Predicting means for predicting a temperature distribution of the heating region of the heating member after heating by the heat source by a predetermined calculation when heating of the heating member by the heat source is started;
Based on the prediction result by the prediction means, one or a plurality of heat generation distributions used for heating the heating member from the plurality of heat generation distributions of the heat generation source and a heating time in the one or more heat generation distributions, Determining means for determining a temperature difference in the heating region of the heating member to be a predetermined value or less;
An image forming apparatus including:   The determining means sets the one or a plurality of heat generation distributions and the heating time to a predetermined time until the temperature difference in the heating region of the heating member becomes a predetermined value or less and is heated to a fixable state. The image forming apparatus according to claim 5, wherein the image forming apparatus is determined so as to fall within a range. A computer that controls a heat source when a heating region of a heating member that fixes a toner image transferred onto a paper together with a pressure member to the paper is heated by a heat source that can switch a plurality of different heat generation distributions. To the device,
A prediction function for predicting the temperature distribution of the heating region of the heating member after heating by the heat source by a predetermined calculation when heating of the heating member by the heat source is started;
Based on a prediction result by the prediction function, one or a plurality of heat generation distributions used for heating the heating member from the plurality of heat generation distributions of the heat source and a heating time in the one or more heat generation distributions, And a determination function for determining a temperature difference in the heating region of the heating member to be a predetermined value or less.   The determination function determines the one or more heat generation distributions and the heating time as a time until the temperature difference in the heating region of the heating member is equal to or less than a predetermined value and is heated to a fixable state. The program according to claim 7, wherein the program is determined to be within a range. In the computer device,
A temperature detection function for detecting the surface temperature of the heating member in a fixable state;
A deterioration detection function for detecting a deterioration of the heating member by calculating a difference between a prediction result by the prediction function and a detection result by the temperature detection function;
The program according to claim 7, further comprising:

Images